Volt-ampere meter



Feb. 2 1926.

AAAAAAAA \1,57l,912 B. H. sMrrH VOLTf-AMPERE METER Original Filed Feb.6, 1922 AA AAAAAA l AAAAM( 2 Vvvvvvv LAAAAAAA vvvvvvv WITNESSES:

Patented Feb. 2, 1926.

UNITED STATES PATENT OFFICE.

BENJAMIN H. SMITH, or WILKINSBURG, rENNsYLvANIA, ASSIGNORTO WESTING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION or PENNSYL- VANTA.y

VOLT-AMPERE METER.

l Application filed February 6, 1922, Serial' N-o. 534,286. RenewedJanuary 7, 1926.

To all 'whom t may concern.'

Be it-lmown that LBENJAMTN H. SMITH, a citizen of the United States, anda resident of I/Vilkinsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Volt-AmpereMeters,-of ywhich the following is a specification.

' My invention relates to electrical measuring instruments andparticularly to instruments for measuring the volt-amperes ofalternating-current circuits.

Y One object of my invention is to provide an instrument ofthe aboveindicated character that shall accurately indicate the volt amperes of acircuit irrespective of changes in the power factor thereof.

Another object of my invention is to provide a volt-ampere-meter devicethat shall comprise few parts and that shall be compact in construction,economical in manufacture and effective in operation.

.I-Iere.tofore, means for measuring` the voltamperes ofalternating-current circuits have `usually been comparativelycomplicated in that they require relatively 'l large numbers of partsandrelatively complicated wiring systems.

In practicing my invention, I provide asingle self-containedtranslating` or motor device,'similar to an ordinary motor, that vmay beso wound, or affected by an auxiliary current transformer ortransformers, and

connected to an ordinary polyphase watt-k meter as to cause the latterto effectively' measure the volt-amperes of the circuit.

Figure 1 of the accompanying drawings 1s a diagrammatic view of a deviceembodying Amy invention, and

`Fig. 2 is a similiar view of a modified form of my invention.

As shown in Fio. comprise, in genera, circuit 1`, shown .as athree-phase circuit but which may suitably be Yof any number of phases,a main current transformer or transformers 2, a meter 4, similar to anordinary wattmeter, a voltage transformer 5, andl a translating device6. The device 6 comprises a movable element or winding 7 that isconnected, through slip rings 8 and conductors 9, to the secondarywiding 10 of the voltage transformer 5. A stationary element or winding11 is connected, by con- 1, my invention may an alternating-currentstationary element 11 are constructed and related to each other andtothe circuit 1 to have fields responsive to the voltage and to thecurrent of the circuit 1, respectively, rotating'in the same direction.This construction permits the element 7 to assume a balanced phaserelation, or position of no torque, with respect to the stationarywinding 11. Thus, if the phase relation between the current and thevoltage of the circuit l changes in either direction, the element 7immediately assumes a position of no torque with respect to the winding11, or a position indicative of the power factor of the circuit 1, andthe current in the conductors 15 is so affected, as to, at the sametime, be in phase with the voltage of the circuit 1.

Since the current element 13 of the meter 4 is energized in accort ancewith the current of the circuit 1, and the voltage element 111 thereofis energized in denite phase relationship to the current traversing thewinding 18, the meter 4 will, at all times,

accurately measure the vo-lt-amperes, irre- 'nsA values of currentnormally supplied by thek transformers 2 and 5, the ampere turns of thewindings 7 and 11 are rendered more nearly equal by increasing thenumber of turns of the conductor in the winding 11.

This construction causes the current and voltage elements 13 and 14,respectively, of

.the meter 4, to be supplied with currents more nearly of the sameorder, to ensure effective operation In the form of my invention shownin? Fig. 2, in which similar parts are designated by similar referencecharacters, the construction is substantially the same as that abovedescribed, with'the exception that the ampere turns Of the elements 7and 11 are rendered more nearly equal by means of an auxiliary step-upcurrent transformer or transformers 3, in the secondary circuit of themain current transformer 2. This per- Cil mits oit the use olt arelatively high-voltage winding Il, whereas the winding 14C of thedevice shown in Fig. l is a relatively lowvoltage winding. In otherwords, by the use oi the step-up transformers 3, a. standard wattmeterl. may be used. The Winding la of the device shown in Fig. l must, ofnecessity, be special, as it has impressed thereon relatively lowvoltage. In this form of my invention, the current elements 13 of themeter -l are connected in star, relative to each other, and in directconnection to the conductors l2 instead ot through the transformers 3,which are omitted.

lVhile I have shown and described particular :terms ot my invention,changes and modilcations may be made therein without departing trom thespirit and scope oft my invention, and such modifications are intendedto be covered by the appended claims.

that I claim as my invention is:

l. In an alternatingcurrent circuit, the combination with a meter, of atranslating device having only one current element and onlyv one voltageelement, said elements being automatically relatively adjustable inaccordance with powenractor changes in the circuit and cti-operatingwith each other only for supplying current to the meter.

Q. In an alternating-current circuit, the combination with a meterhaving a current element energized in accordance with the current ol.the circuit and a voltage element, of a translating device having onlyone current element and only one voltage element, said elements beingautomatically relatively adjustable `in accordance with power-factorchanges in the circuit and cooperating with `each other only forenergizing the meter voltage element.

il. In an alternatingcurrent circuit, the combination with a meterhaving a current element energized in accordance with the current of thecircuit and a voltage element, of a translating device` 'lor tansmittingcurrent to the voltage element comprising a winding directly responsiveto the current and inductively responsive to the voltage of the circuit.

+L. In an alternati11g-current circuit, the combination with a meterhaving a current element energized in accordance with the current of thecircuit and a voltage element, of a translating device for transmittingcurrent to the voltage element comprising windings, one ol' which isdirectly responsive to the current of the circuit and is connected tosaid voltage element and the other of which. is responsive to thevoltage of the circuit and is inductively related to the currentwinding.

5. In an alternating-current circuit, the combination with a metercomprising co-operating elements, one of which is directly connected tothe circuit, of a translating device comprising inductively relatedrelatively movable current .and voltage elements, one of which isdirectly connected to the other meter element.

G. In an alternatingcurrent circuit, the combination with a meter, of atranslating device including only two inductively related windings, saidwindings being relatively movable by the inductive ell'oit thereof inaccordance with power-factor changes in the circuit Yfor supplyingcurrent to the meter.

7. In an alternating-current circuit, the combination with current andvoltage transformers, and a meter having current and voltage coils` ot atranslating device having a movable winding connected to the voltagetransformer and a stationary winding energized from the currenttransformer, said windings being related to cause rotating fields in thesame direction and said meter voltage coil being connected to saidstationary winding.

El. The combination with a meter having current and voltage coils, of atranslating device having a winding energized in accordance with thevoltage of a circuit and a secondary winding energized in accordancewith the current of said circuit, said windings being related to causerotating fields in the same direction and said meter voltage coil beingconnected to said second winding.

9. In an alternating-current circuit, the combination with a metercomprising co-operating current and voltage windings one of which isdirectly energized from the circuit, ot a translating device comprisinginduetively related current and voltage elements relatively movable inresponse to power-factor changes and one ot which is directly connectedto the other meter winding.

In testimony whereof, I have hereunto subscribed my name this 26th dayoi. January 1922.

BENJAMIN H. SMITH.

